Trouble understanding orbital hybridization

[thomasxc]

As the title suggests, i am having difficulty understanding orbital hybridization, as well as pi and sigma bonds. Can someone help me out and/or point me in the right direction? Thanks


Tom

 

[cdotter]

http://chemistry.boisestate.edu/people/richardbanks/inorganic/bonding%20and%20hybridization/bonding_hybridization.htm
http://www.chem1.com/acad/webtext/chembond/cb07.html

 

[thomasxc]

so orbitals become hybridized because of electron repulsion?

 

[cdotter]

so orbitals become hybridized because of electron repulsion?

Sorry, I should have included this link as well. http://www.chem1.com/acad/webtext/chembond/cb06.html Orbitals hybridize to allow bonding in atoms that otherwise wouldn't be able to form the bonds they do (see the beryllium example in the above link.)

 

[thomasxc]

that one helps a bit. and what about pi and sigma bonds?

 

[nickdk]

All single (covalent) bonds are sigma bonds, and every bond after that is pi bonds. For example: If you have carbon bonded to four hydrogen atoms, then you have 4 single bonds, therefore you have 4 sigma bonds. Where as if you have elemental Nitrogen (N2), you have a triple bond, so there is 1 sigma bond in the triple bond, and the other two are pi bonds.

Single bond = 1 sigma bond
Double bond = 1 sigma bond + 1 pi bond
Triple bond = 1 sigma bond + 2 pi bonds

 

[thomasxc]

All single (covalent) bonds are sigma bonds, and every bond after that is pi bonds. For example: If you have carbon bonded to four hydrogen atoms, then you have 4 single bonds, therefore you have 4 sigma bonds. Where as if you have elemental Nitrogen (N2), you have a triple bond, so there is 1 sigma bond in the triple bond, and the other two are pi bonds.

Single bond = 1 sigma bond
Double bond = 1 sigma bond + 1 pi bond
Triple bond = 1 sigma bond + 2 pi bonds

i understand this, (i think) but i am confused as to their orientation in reference to each other. my ap chem teacher made it seem like one surrounds/revolves around the other, but when i asked that specifically, he said no.

 

[cdotter]

that one helps a bit. and what about pi and sigma bonds?

Sigma bonds are formed by the end-to-end overlapping of orbitals. Pi bonds are formed by the side-to-side overlapping of orbitals.

 

[cdotter]

i understand this, (i think) but i am confused as to their orientation in reference to each other. my ap chem teacher made it seem like one surrounds/revolves around the other, but when i asked that specifically, he said no.

What do you mean by orientation?

 

[thomasxc]

the diagram he showed us made it seem like one orbital was in the middle, while the other had the ability to be anywhere around it. perhaps incorrectly, i took that to mean it might revolve or rotate around it.

 

[thomasxc]

and then he said it was somehow similar to resonance, which served only to confuse me more:/

 

[Char. Limit]

The pi orbital is perpendicular to the sp2 orbitals in an sp2 atom, and the two pi orbitals are perpendicular to each other and to the sp orbitals in an sp atom.


Too confusing? We'll, I always tell myself I'd suck at teaching...

 

[renob]

If you have a good general chem book then it basically just takes a lot of reading until you understand these concepts. This section for me, along with entropy were the hardest parts about chem 1 so far.

Just remember that the central atom of the molecule must make enough hybrid orbitals to accommodate any bonded atoms and lone pairs attached to the central atom.

 

[Borek]

You may think about it this way: sigma bond links centers of the atoms, they are like balls connected with a rod. This rod can rotate. Place in the middle is already occupied, so pi bonds must be on sides - that means additional rods, parallel to the first one (I see it as a two thinner rods on two sides, as lobes of p orbitals stick out). Now construction becomes rigid. Second pi bond will be similar, it just lies in the plane perpendicular to the plane where first pi bond lies.

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